Definitely split them down.
Rough out a bow, leave the bark on if possible. Then seal very, very well, strap to a board to prevent warpage and cross your fingers!
You want to leave them somewhere shady, with little air movement and cool.
Once they have lost a decent bit of moisture, reduce to floor tiller and allow to season fully. It will take a few years. Apple is funny stuff but well seasoned it is very good.